1. Field of the Invention
The present invention relates to an antenna array and, more particularly, to an array wherein the individual antennas are each connected by a separate RF (radio frequency) line to a switching device for activation.
2. Description of the Prior Art
An antenna array of the above-mentioned type is described in a book entitled "Funksysteme fur Ortung und Navigation", Verlag Berliner Union GmbH, Stuttgart, 1973, on pages 139 to 145.
The antenna array is described there in connection with a Doppler VHF omnirange (Doppler VOR). It contains several omnidirectional antennas arranged on a circle.
In navigation systems, such as the Doppler VOR, it is of utmost importance that the RF signals be radiated exactly in the manner prescribed.
If, for example, a signal is to be radiated from only one antenna at a time, this is nearly impossible with a small antenna spacing. RF energy from the radiating antenna also reaches the adjacent antennas, which act as parasitic radiators.